Traditional door lock faces, which have a flat surface with a reception slot for a key, have presented a challenge to users who have difficulty with aligning the key with the reception slot. The task is particularly troubling for the elderly and those with failing vision and is even a chore in unlighted areas for otherwise capable individuals.
Systems have been developed to assist in the alignment of keys with associated reception slots. For example, a key guide proposed by Baccolla in U.S. Pat. No. 2,993,362 provides a generally conical surface tapering toward the key slot to direct an inserted key toward the slot. To orient the key angularly with the slot, the conical surface has a groove along its length. However, the user must orient the key blade on the groove with much the same effort as would be required to align with the slot of the keyhole itself. A groove provided by an alternative guide of Baccolla that has inclined surfaces leading to the groove likewise requires proper angular orientation of the blade with the groove.
Grinage, in U.S. Pat. No. 4,295,350, and Rosenthal, in U.S. Pat. No. 4,821,542, also disclose guides having conical surfaces leading toward a lock keyhole, but both rely on the user for angular alignment of the key and the keyhole. U.S. Pat. No. 2,941,392 to Byrne and U.S. Pat. No. 5,109,686 to Toussant teach keyhole guides having inclined surfaces directed toward the keyhole but, again, do not alleviate an angular misalignment without user intervention. The angular rotation by the user may cause jamming in the guide structure of these prior art systems, obviating the intended assistance to be provided by these guides.
It is desirable to have a key guide that not only directs an inserted key toward the keyhole of the lock but also automatically aligns the key, when turned, angularly with the slot during the insertion process, independent of the initial angle or location of insertion into the guide.